Carburetor



May 20, 1930. H. o. CRAM 1,759,040

' CARBURETOR Filed Jan. 21, 1925 2 Sheets-Sheet 2 Patented May 20, 1930 UNITED STATES HARRY O. CBAM, F BRIDGEPORT, CONNECTICUT GARBURETOR Application filed January 21, 1925. Serial No. 3,743.

This invention relates to carburetors for internal combustion engines, an object of the invention being to provide an improved relatively simple and compact carburetor so con- 'i'. structed as to more efficiently and properly supply a correct fuel mixture to the engine throughout the range of operation of the engine.

A further object of this invention is to provide an improved carburetor in which the carbureting or mixing chamber thereof comprises a plurality of separate or independent mixing chambers or ducts having a plurality of inlets through which fuel and air are supplied, and wherein means is provided for varying the capacity of the carbureting chamber by independently closing and opening one of the mixing chambers or ducts in proportion to the requirements of the engine. 110 One of the features contemplated by this invention is the provision of a carburetor having for instance substantially two separate mixing chambers, one adapted to be used alone when the engine is throttled down fully, and both adapted to be used to capacity when the throttle is wide open. Under operating conditions between these extremes, provision is made for gradually opening or closing one of the mixing chambers in pro.- portion to the requirements of the engine. Provision is also made for utilizing the exhaust gases of the engine to assist in carburetion, the carbureting chamber, comprising a plurality of ducts of different sizes,'being surrounded by a heating chamber which is effective to'heat the fuel passing through the smaller ducts to a greater degree thereby enabling the fuel mixture to be heated properl under different operating conditions.

ther objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification, wherein like reference characters designate corresponding parts in the several views, and wherein Fig. 1 is a central vertical section of this improved carburetor; Fig. 2 is a detail sectional view taken substantially on line 44 of Fig. 1 looking in the direction of the arrows in said Fig. 1:

Fig. 3 is a cross section taken substantially on line 5-5 of Fig. 1; Fig. 1 is a front ele vation of this improved carburetor; and Fig. 5 is a left-hand view of the carburetor shown in Fig. 1.

Before explaining in detail the present improvement. and mode of operation thereof, I desire to have it understood that the invention is not limited to the details of construction and arrangement of parts which are illustrated in the accompanying drawings, since the invention is capable of other embodiments, and that the phraseology which I employ is forthe purpose of description and not of limitation.

The carburetor in the present preferred. form herein shown and described comprises a body or casing 9 preferably in a single casting and having at opposite sides thereof openings 10 and 11. Within the casing 9 is formed a heatingchamber 12. Connected to the openings 10 and 11 which communicate with the heating chamber 12 are pipes 13 and 14 respectively which are secured in place 7 by means of collars 15 bolted to the casing 9 and screwed on to the ends of the pipes, as shown in Fig.

Centrally formed within the casing 9 and surrounded by the heating chamber 12 is a carbureting or mixing chamber 16. In the o present instance this comprises a relatively large straight duct 17 terminating at its bottom in an inlet opening 18, and which, because of its size, will be for purposes of designation termed the main duct or chamber. The carbureting chamber also comprises a series of relatively small duct-s 19 which arearranged at one side of and partly around the duct or passage 17 as shown clearly in F g. 3, and which will be, for purposes of des1gnation, termed auxiliary or independent ductsf The ducts 19 at thebottom 20 thereof terminate at a point somewhat above the bottom of'the duct 17 (see Fig. 1), and open into a chamber 21 which terminates in an inlet opening 22. The inlet openings 18 and 22 are located in the same horizontal plane and in the present instance these openings have substantially the same diameter. Thus 1t w1ll be seen from this construction that the inlet 18 for the duct 17 has substantially the same size as the inlet 22 for the several ducts 19.

Below the carbureting or mixing chamber the carburetor is provided with an air intake pipe or passage 23. A nipple 24 is located in the end of the pipe 23 and is provided at one side with an opening or orifice 25 through which air is admitted. A sleeve 26 surrounds the nipple 24 and is provided with an open ing adapted to register with opening 25.

This sleeve is held in position by means of a thumb screw 27, and by loosening the screw the sleeve may be rotated to vary the amount of unheated air admitted into the air intake pipe. Connected to the upper end of the pipe 23 is a casing which is mounted on the exhaust pipe 14 and forms a hot air jacket adapted to heat the air entering the carburetor.

The several ducts 17 and 19 at the upper ends thereof terminate in a common opening 29, and the casing 9 is provided with a flanged portion 30 which is adapted to be bolted at 31 to a corresponding flange 32 carried by a pipe 33 which leads to the intake manifold of the engine. Carried by the base portion 34 of the carburetor are a pair of spray 'nozzles 35 and 36. The orifice 37 of spray nozzle 35 is located within the mouth or inlet 18 of the large duct 17, and the orifice 38 of the spray nozzle 36 is located within the inlet opening 22 for the several ducts 19. It will be noted that-the stems of the spray nozzles 35 and 36 are centrally alined with the inlets 18 and 22. These spray nozzles may be of any suitable construction and in the present instance the needle valves controlling the outlet orifices thereof are adjustable by means of handles 39 and 40 respectively. The base portion 34 of the carburetor is bored at 41 and a pipe 42 communicates with this bore for the purpose of supplying the spray nozzles with fuel from a float chamber 51.

Located in the outlet 29 is a valve 43 which in the present instance is of the butterfly type. This valve is mounted on a pivot pin 44 extending through the wall of the casing. Connected to the outer end of this pin or spindle 44 is a two-armed lever by means of which the valve 43 is operated. One arm 45 of this lever has the usual operating connection and the other arm 46 is connected by means of a link 47 to a lever or arm 48 secured to a pivot pin 49. This pin or spindle extends through a wall of the casing into the 'lower end of the duct 17, and connected thereto is a throttle valve 50.

From the foregoing it will be noted that upon swinging the lever arm 45 the throttle 43 will be swung on its pivot 44, and at the same time by means of the connections between lever 45 and lever 48 the throttle 50 will at the same time be swung on its pivot 49. The construction of the connecting members between the main throttle 43 and the auxiliary throttle 50 are such that the latter will be in horizontal position as shown in Fig. 1 when the main throttle 43 is partially open. In this position of the throttle valves the engine will be fully throttled down, the throttle valve 50 acting to close or shut off the duct 17. When the main throttle 43 is in vertical position and wide open the throttle 50 by virtue of the link connections will also be in substantially vertical position and therefore Wide open.

When the main throttle 43 is gradually closed thereby decreasing the speed of the engine, the throttle 50 working in conjunction with the main throttle gradually limits or shuts off the flow of fuel and air through the large tube or duct 17. Thus as the speed of the engine decreases the action on the fuel nozzle 35 gradually decreases, or in other words as the speed decreases, the suction is gradually taken away from one nozzle 35 so as to act more fully on the other nozzle 36. When the speed of the engine is lowest, the throttles being in the position shown in Fig. 1, the suction acts entirely on the nozzle 36. The effect of this operation is to insure practically a uniform velocity of air through the inlets 18 and 22 into the carbureting chamber. As the main throttle 43 is opened and the flow of air increases in volume an increasing portion of this volume of air is gradually d1.- verted to the inlet, 18 around the nozzle or fuel jet 35, so that when the throttle is wide open the air velocity is the same as when the throttle is closed, since the capacity of the carburetor has been increased in proportion so as to handle the increased volume of air drawn through the intake.

In the present construction it will be noted that I have provided a carbureting chamber which in all substantial respects comprises two separate mixing chambers, one being the tube or duct 17, and the other the several tubes or ducts 19, each thereof having a fuel nozzle. 'When. the throttles are wide open the suction of the engine acts upon both fuel nozzles 35 and 36, and when the engine is throttled down entirely the suction thereof acts upon fuel nozzle 36 alone. Thus, assuming that the combined capacity of the ducts or tubes 19 is the same as the capacity of the duct or tube 17 it will be noted that when the throttles are wide open the main carbureting chamber herein will have twice the capacity as when the engine is fully throttled down. In the case of a 1 inch carburetor, that is a carburetor in which the outlet passage 29 is 1% inches in diameter, the combined area of the small passages 19 will be substantially the same as the area of the passage 17 and the combined area of all the passages 17 and 19 will be substantially the same as the outlet the ca acity of thecarburetor when the passage 1 is open.

This improved carburetor, I have found by actual test under working conditions, will supply the correct proportions or ratio of air and fuel at all times. It is commonly understood that the proper proportions or ratio is 1 to 15, that is 1 offuel and of air, and in this improved carburetor, substantially this same ratio is maintained thru the small passages 19 when the large passage 17 is closed.

. In carburetors heretofore in use, the most common means used in trying to maintain this proper rat-i0 when the, engine is throt tled down is a spring air valve or an a-uX-' iliary fuel passage or port, neither of which have been entirely successful, but in the present] improvement actual tests have shown that the same ratio or correct proportions of air and fuel are maintained thru the smaller ducts 19 when the engine is throttled down, or when the main passage 17 is fully closed. From the foregoing it will be noted that conditions.

in the present carburetor there is no fixed subjected to widely varying pressures, and

it has been found that'the varying action on the fuel jet did not enable a properly pro portioned mixture to be .obtained under different conditions of operation.

Heretofore in order to obtain the correct amount of fuel throughout the diflere'nt speeds of the engine auxiliary means was provided to compensate for that condition. For instance in some cases spring tension air valves are utilized or in other cases more complicated means employed in an efiort to get a correct mixture of air and gasoline under various conditions. That none of these present-day carburetors supply a jcorrect mixture at all times is evidenced by the fact that the great difl'iculty experienced ,in presentday engines results from unburned fuel passing down the cylinder walls into the crank case. bric'ating oil in'engines must be withdrawn frequently and a fresh supply substituted.

In the present carburetor a uniform velocity'of air around the fuel jets is obtainedundcr all conditions. WVhen the throttles are wide open and the suction of the engine greatest, the air coming through the intake 23 will This has been so serious that the lu-' enter the mixing chamber through both inlets 18 and 22. When the engine is fully throttled down and the suction is lowest, the air inlet 18 is shut off and the air will pass through inlet 22 alone. At the same time this suction acts upon the single fuel jet 36 and a proper-proportioh of fuel and air isobtained under all conditions. At thesame time it will be noted that the air and fuel will be heated to a greater extent under throttled conditions 'than under conditions where the throttles are wide open, since when the gases are passing through the small tubes 19 they will be heated to a greater extent, than when passing through the tube 17 as. well. Thus, it will be seen thatwhen the engine is gradually throttled down, the capacity of the carbureting chamber is gradually reduced and atthe same time the gases are gradually heated to ya. greater extent.

It is to be understood that by describing in detail herein any particular form, structure or arrangement, it is not intended to limit the inventionvbeyond the terms of the several claims or the requirements of the prior art.

Having thus explained the nature of my sa'id invention and described a way of constructing and using the same, although without attempting to set forth all of the forms in which it may be made, or all of the modes of its use, I claim:

1. A carburetor comprising a mixing chamber Within a heating chamber, the mixing chamber comprising a main duct having an air inlet and a plurality of independent ducts all having an independent but common air inlet, all of said ducts extendingthrough the heating chamber and having a common outlet, a pair of fuel nozzles, one'for each inlet,

whereby one nozzle is in communication with one duct and the other in communication with all of the remaining ducts, throttling means for the outlet, and positively controlled means located adjacent to one of said nozzles for gradually or entirely cutting ofl the supply of fuel from said nozzle. I 2. A carburetor having a mixing chamber within a heating chamber, the mixing chamber comprising a main duct having an air inlet and a plurality of independent ducts all having an independent but common air inlet, all of said ducts extending through the heating chamber and having a common outlet, said independent ducts being all located at one side only of the main-duct, an independent fuel nozzle for each inlet, throttling means for the outlet, and means interconnected with said throttling means located at the lower end of one duct and adjacent to one of said nozzles for graduallyor entirely cutting off the supply of fuel from said nozzle.

3. A carburetor having a mixin chamber within av heating chamber, the mixing chamber'comprising a main duct having an air inlet and a plurality of independent ducts all having an inde 'endent but common air inlet, all of said ucts extending through the heating chamber and having a common ed at the lower end of the lon er duct and "adjacent to one of said nozzles or gradually or entirely cutting oif the supply of fuel from said nozzle.

4. A carburetor having a mixing chamber within a heating chamber, the mixing chamber comprising a main duct having an air inlet and a plurality of independent ducts all having an independent but common air inlet, sald inlets having substantially the same size, all of said ducts extending through the heating chamber and having a common outlet, a pair of fuel nozzles,'one for each inlet, whereby one nozzle is in communication with one duct and the other in communication with all of the remaining ducts, throttling means for the outlet, and positively controlled means interconnected with said throttling means and located adjacent to one of said nozzles forgradually or entirely cutting off the supply of fuel from said nozzle.

5. A carburetor having a mixing chamber within a heating chamber, the mixlng chamber comprising a main duct having an air inlet and a plurality of independent ducts of smaller diameter all having an independent but common air inlet, said inlets having substantially the same size, all of said ducts extending through the heating chamber and having a common outlet, said independent ducts being located to one side of the main duct and having less length than the main duct a chamber located betweensaid independent ducts and the inlet thereof, an independent fuel nozzle projecting into each inlet, and interconnected valves located adjacent to the outlet and to that nozzle supplyin the main duct for throttling the outlet an for graduall or entirely cutting off the supply of fuel rom said nozzle, thereby glradually or entirely forcing the fuel throu smaller ducts, whereby it becomes more higfily heated.

6. A carburetor having a mixing chamber within a heating chamber, the mixing chamber comprising a main duct having an air inlet and a plurality of independent ducts of smaller diameter, all having an independent but common air inlet, all of said ducts ,extending through the heating chamber and having a common outlet, a pair of fuel nozzles, one for each inlet, whereby on e nozzle is in communication with one duct and the other in communication with all of the re maining ducts, and means located adjacent to the outlet and to that nozzle supplying the main duct for throttling the outlet and for gradually or entirely cuttin off the sup 1y of fuel from said nozzle am? thereby ra ually or entirely forcing the fuel throug that part of the mixing chamber whereby it becomes more highly heated.

7. A carburetor comprising a mixing chamber formed of a plurality of independent ducts of different diameters having independent air inlets and a common outlet, means for heating said mixing chamber thereby to more highly heat the fuel mixture in one part than'in another part thereof, a pair of fuel nozzles, one for each inlet, wherey one nozzle is in communication with one duct and the other in communication with all of the remainin ducts, and means for gradually cutting 0 one of said ducts thereby gradually reducing the capacity ofthe mixing chamber and means interconnected with said last means for at the same time forcing the fuel only through the part of the mixing chamber where it becomes more highly heated.

8. A carburetor comprising a mixing chamber formed of a main duct having an air inlet and a plurality of independent smaller ducts all at one side only of said main duct and all having an independent but common air inlet, all of said ducts having a common outlet, means for heatingsaid mixing chamber, an independent-fuel nozzle for each inlet, and a pair of interconnected throttle valves one controlling the outlet and the other the nozzle for the main duct and operative to gradually cut off said main duct and thereby gradually reducing the capacity of the mixing chamber and at the same time forcing the fuel to pass onl through the smaller ducts whereby it becomes more highly heated.

9. A carburetor comprising a mixing chamber formed of a main duct having an air inlet and a plurality of independent smaller ducts at the side of said main duct and all having an independent but common air inlet, all of said ducts having a common outlet, means for heating said mixing chamber, an independent fuel nozzle for each inlet, athrottle valve located in the outlet, :1 throttle valve located adjacent to the inlet and nozzle of the main duct, and means connecting said throttle valves for simultaneous operat1on to cause one of the valves to have a greater range of movement'than the other and operative to gradually cut off said main duct and its nozzle and thereby gradually reducing the capacity of the mixing chamber and at the same time forcin the fuel to ass only through the smal er ducts where y it becomes more highly heated.

10. A carburetor comprising a casing having an air inlet and having within said casing a combined heating and mixing chamber comprising a plurality of independent pas-- turef rom all of said passages, means in said outlet for controlling the quantity of fuel mixture passing therethrough, a pair of nozzles within said casing, each alined with one of said inlets, means for conveying fuel to the nozzles, and means also within said casing and interconnected with said outlet controlling means for varying the quantity of fuel passing through one passage with relation to said plurality of passages.

11. A carburetor comprising a casing having an air inlet and having within said casing a combined heating and mixing chamber comprising a plurality of independent passages all within the heating chamber and of different diameters whereby, the fuel. mixture passing through certain of them becomes more highly heated and a plurality of said passageshaving a single inlet and one of said passages having an independent inlet, a pair of nozzles within said casing for independently supplying fuel to said inlets, and means also within said casing for varying the quantity of fuel through one inlet with relation so to the other whereby the fuel will pass through the passages where it becomes more highly heate 12. A carburetor having therein a mixing chamber within a heating chamber, the mix- 8 'ing chamber comprising a plurality of ducts,

means for supplying a mixture of air and fuel to and through said ducts at a certain ratio and heated to a certain degree one of said means in communication with one of said ducts and the other in communication with all of the remaining ducts and positively-controlled connected means for closing certain of said ducts and maintaining the same ratio of air and fuel through the other ducts but heated to a higher, degree.

13. A carburetor having therein a mixing chambenwithin a heating chamber, said mixing chamber comprising a plurality of fuel passageways, means for heating the fuel mixture passing through certain of said fuel passageways to a greater extent than others, means for supplylng a mixture of air and fuel to said passageways at a certain ratio and positively-controlled connected butterfly valves for closing certain of said passageways and maintaining the same ratio of air and fuel through the other passageways while increasing the heat of the fuel passing through said last passageways.

14. In a carburetor, a mixing chamber comprising a plurality of fuel passageways 'of different diameters, means for heating all of said fuel passageways and the fuel passing through certain thereof to a greater extent of air and fuel through said passa eways at a certain ratio, a plurality of nee e-valvecontrolled fuel supply nozzles and air inlets for independentl supplying a mixture of air and fuel to sai passageways' at a certain proximately the same level, means for closing one of said passageways adjacent its lower end. and maintaining the same ratio of'air and fuel through other passageways while increasing the heat of the fuel passing through said last passageways.

a 15. A carburetor comprising a plurality of heated mixing chambers, each mixing cham-- ber havingan inlet and each having'substano ratlo, sa1d needle-valves being located at aptially the same area, means for supplyin air and fuel to said inlets, said mixing cham ers having a common outlet substantially'corresponding to the combined area of all the mixing chambers, 11 throttle valve in' said common outlet, and a throttle valve connected for operation with first throttle valve for controlling one of'said mixing chambers, the" 1 organization being such that when said last.

throttle valve is c sed the same ratio ofair and fuel will be maintained in theother mixing chamber.

16. In a carburetor,-a carbureting chamber within aheating chamber, said carbureting chamber coniprisin a plurality ofseparate ducts of different 'ameters having a common outlet and a plurality. of fuel inlets,

means for heating all of said ducts and the fuel passing through certain thereof to a greater extent than others, a plurality of fuel nozzles and air inlets for supplying air'and fuel to said fuel inlets at a certain ratio, one

of said fuel nozzles in communication with havin an air inlet and a group of smaller ducts aving an independent but common air inlet, all of said ducts passing thru the heating chamber, an independent fuel nozzle for each inlet, a common outlet passage for the fuel mixture fromall of'said ducts,'throttling means for said outlet, throttlin means at the lower end of one duct 'anda jacent to one of said nozzles, and positively controlled means for operating both of said throttling means to gradually or entirely out o'fi'the supplyof fuelfrom said throttle controlled nozzle as the fuel supply from said outlet is gradually but not entirely out off.

' 18. A carburetor combining a fuel mixing chamber within a heating chamber, ,the fuel mixing chamber comprising a main duct having an air inlet and a group -of smaller ducts having an independent but common air inlet, all of said ducts passin thru the heating chamber, an independent uel nozzle for each inlet, a common outlet passage for the fuel mixture from all of said ducts, throttling means for said outlet, throttling 10 means at the lower end of one of said ducts and adjacent to one of said nozzles, and a single positively controlled means for operating both of said throttling means to radually or entirely out off the supply'of uel from said throttle controlled nozzle as the fuel supply from said outlet is gradually but not entirel cut off.

19. carburetor combining a fuel mixing chamber within a heating chamber, the fuel 29 mixing chamber comprising a main duct having an air inlet and a group of smaller ducts all located to one side only of the main duct and having an independent but common air inlet, allof said ducts passing through the 5 heating chamber, an independent, needle valve controlled, fuel nozzle for each inlet, said needle valves being located at approximately the same level, a common outlet passage for the fuel mixture from all of said 30 ducts, throttling means for said outlet, throttling. means ad acent to one of said nozzles, and positively-controlled means for operating both of said throttling means to gradually or entirely out off the supply of fuel from said throttle controlled nozzle as the fuel supply from said outlet is gradually but not entirely cut off. .Signed at Bridgeport, Connecticut, this 10th day of January 1925. HARRY 0..CRAM. 

